Today, the world economy is mainly built on the basis of fossil energy, such as coal, oil and natural gas. However, the non-renewable fossil energy is constantly depleting. Since the beginning of the 21st century, global energy issues and the consequent issues about environmental pollution and global warming become more apparent and gradually intensified. Solar energy has the outstanding advantages such as widespread and broad distribution, large amount, pollution-free, clean, safe and convenient obtained, so it is considered to be one of the most promising renewable energy. Solar cells transfer the solar energy into electricity directly, which is an effective and feasible method of using solar energy. However, the current commercial solar cells are restricted to silicon and other inorganic solar cells, while their prices are so expensive that exceed general acceptable degree currently, which greatly limit their use. In order to reduce the cost and expand the scope of application, for a long time, people have been looking for the new solar cell materials.
Organic solar cells is a new type of solar cells, compared with the inorganic semiconductor materials of the limited source, expensive price, toxicity, complex preparation process and high cost, it has some advantages that inorganic solar cells can not match, such as wide sources of materials, diversity and regulation of the structure, low cost, safety and environmental protection, simple preparation process, light weight, and can be flexiblly prepared in large areas, etc., which can be widely used in the field of architecture, lighting and power generation, with important development and application prospects. Therefore, many domestic and international research institutions and enterprises are all given considerable attention and investment to it. So far, however, the photoelectric conversion efficiency of the organic solar cells is much lower than the inorganic solar cells's. Therefore, it has great significance for improving the efficiency of the organic solar cells and other semiconductor devices that the development of new organic photoelectric materials.